Automatic telephone switches having means for limiting the testing interval



April 1960 HANS-JOACHIM JABCZYNSKI 2,933,562

AUTOMATIC TELEPHONE SWITCHES HAVING MEANS FOR LIMITING THE TESTING INTERVAL 2 Sheets-Sheet 1 Filed March 9, 1953 April 1960 HANS-JOACHIM JABCZYNSKI 2, 3 6

AUTOMATIC TELEPHONE SWITCHES HAVING MEANS FOR LIMITING THE TESTING INTERVAL 2 Sheets-Shet 2 Filed March 9, 1953 a &6

AUTOMATIC TELEPHONE SWITCHES HAVING MEANS FOR LllVIlTlNG THE TESTING IN- TERVAL Hans-Joachim Jabczynsld, Berlin-Zelendorf, Germany,

' assignor to Siemens & Halske Aktiengesellschaft,

Munich, Germany, a corporation of Germany Application March 9, 1953, Serial No. 341,114 Claims priority, application Germany March 14, 1952 7 Claims. (Cl. 179-18) according to the invention is that the discharge tubes can becomeoperative to stop the switch wipers in engagement with an idle line, under control of a potential which marks the idle condition thereof, only in the simultaneous presence of an auxiliary or additional potential acting on the tubes, such additional potential being for each line reached by the wipers of the corresponding switch over bank contacts connected only once during an interval determined by'the movement of the wipers with respect to the bank contacts during which interval the stopping of the switch wipers can be reliably obtained. I

The various objects and features of the invention will be explained with reference to the accompanying drawings Figs. l-3 showing in diagrammatic manner embodiments in connection with switches comprising wipers which are operated by a plurality of alternately actuated magnets.

Fig. 1 shows only the test or private wiper c and the control wiper d of a selector switch RW. The line wipers which are disposed in the talking path have been omitted.

The switch RW is a well known motor-operated switch comprising two drive magnets which are alternately closed and opened 'under control of the switch operation. An example of a motor for a switch of this kind is disclosed in US. Patent No. 2,002,546, dated May 28, 1935; an

example of a switch is disclosed in Patent No.

2,701,824, dated February 5, 1955;

The switch RW is seized for extending acall, for

I United States Patent '0 example, by a preceding switching device, causing in" well known manner actuation of a seizure relay (not 'shown) which closes contacts such as contacts 10 and 2c. Responsive to closure ofc'ontact 1c, the drive magnets M and M each having two windings indicated re-' speetively by Mil, M II and M 1, M ll, are by contacts m and "1,, which are mechanically controlled during the switch operation, over their windings M 1 and M l,

so affected that the magnet M (winding M 11) is initially in an operating circuit over the contact m thereby rotat-- ing the armature which drives the switch shaft, until the 'armaturebecomes affected by the magnet M (M 1) I 2,933,562 Patented Apr. 19, 1960 7 '2 mined by setting a switch MW in accordance with the number dialled, whereby this switch may be set with its wiper in engagement with the contacts 1, 2 or 3. The switch MW may be set in any suitable and desired known manner; the precise actuation or mode of operation of switch MW has no bearing on the invention. The various trunk or line groups are marked by brief impulses P P which are at different times periodically transmitted by a generator. In accordance with the wiring scheme shown in the drawing, there will be at the contact 1 of the switch MW, at a definite instant, the impulse P at the contact 2, at a definite other instant, there will bank contact of the switch MW will also appear at the corresponding bank contact associated respectively with trunk groups I, II and III, accessible to the wiper d of the switch RW.

If it is assumed that the wiper of the switch MW. is set on the contact 2, the impulse P will appear on the grid G of the discharge tube R0 and at the same time on the grid G at the instant when the wiper dot the switch RW namely, wiper d (RW) sweeps over the segmental contact II; At the grid G is connected 76 volts in a circuit extending over the resistors Wiq and Wig, windings II of the magnets M and M (marked M 11 and M il), and'resistors Wig and Wiz- Also connected to the grid G after the setting of the switch MW on bank contact 2, will be 76 volts over a circuit including the resistor Wi Therefore, at the instant when the impulse P appears (+6.volt), the potentialat the gridG will be-raised to 70 volt This potential on the grid 6, is opposed by a potential induced'iii the windings not the magnets M and M (marked M 11;

M II) (e.g., +10 volt) due to actuation of the control group) there will be upon appearance of the impulse P, (+6 volt) a potential of volt at the same time as it appears at the grid' 6;.

If the switch wiper c of the switch RW engages at such instant bank contact of an idle line in the group H, the idle condition of which is marked by a potential of -60 volt over a resistor Wi the identical potential of -60 volt will appear at the cathode of the tube R0 and such tube will become conductive. i Y 7 Inasmuch as the opposing potential (e.g., +1Q volt) which is induced in the magnet windings M 11 and M 11 appears thereon, asalready mentioned only for brief instant and only once when the switch wiper c engages such armature is again affected by the magnet M, (winding M 1) which in the meantime has become connected over the contact m, by the switch rotation. The contact m, is thereby opened again.

The stopping is effected in a manner to be presently explained, upon energization of relay P which operates its contact 3p to cause energization of both magnet windings M 1 and M 1.

The wipers of the switch RW, which is operable as above described, has access to three groups of bank contacts which are respectively connected with groups of lines or trunks I, II and III. The desired group is deterthe bank contact connected with such line, while disappearing during the further sweep of this switch wiper, the above indicated potential conditions at the electrodes of the tube R0 will be present only for a brief instant. The characteristic of the opposing potential is therefore such that the grid G receives the opposing potential (e.g., +10 volt) only for a certain time interval (testing time) during the engagement of the wiper c with a bank 'contact. This testing interval terminates when a reliable stopping with the wiper c on the corresponding bank contact is not possible. There is, accordingly, a close connection between the testing time (interval) and the testing operation that must be concluded within such interval. If there is no idle test during such interval,

. the switch will move the wiper c to the next followin bank contact and the operations are repeated.

Iv a The relay? closes its contact nated line' groups.

: assam I nection'with Figs. 1 and 2. ontact p6 will again main- 7 t'ain busy potential on the seized line. The initial busy M and M over their coils M land M 1, thereby stopping the switch .RW as already described. V

Whenthe tube R passescurrent there will appear over its dischargepath and the idleline reached by the wiper c a current causing a breakdown of. the potential of 60 volt to the conducting potential of. the tube, e.'g., I

to -16 volt. This latter potential is now on theprivate conductor of the seized line forming a busy potential therefor. The resistance of the primary winding of the a transformer may be neglected; and the seized. line is terminates at an instant be accomplished.

therefore busied within an interval determined by the current risein'the testing circuit. v I r v a spbefore opening contact 4p (make-before-break), thereby completing a holding circuit for its own winding over the closed contact Contact 4p, upon opening, extinguishes the tube R05. At contact 6p, the relay P connectsa busy potential for theseized line and thetube R0} is 'ac'cordin gly extinguished; a I a The operation of the switch RW shown'in the example illustrated in Fig. 2 is-controlled in the same manner as explained with reference to Fig. 1. The potential -6 l volt) which serves fordefining the testing time is again induced in the windings II of the magnets M and; M marked M 11 and M II, respectively. However, this induced potential does not act as an opposing potential on the grid G of the discharge tube R0 but acts additively for the purpose of bringing'the. cathode potential ofithe discharge tube Ro 'together withthe idle potential inf-1 ,60 volt over the resistor Wi to the potential 66 volt as soon asthe wiper c finds. an idle line in the desig- The identical potential oil-66 volt fwill appear on the grids G and G of the discharge tube R0 in a case for example, when the. group II has been potential which appears at the private conductor of the seized line atrthe instant of firing of the tube R0 is as inthe former cases the potential at which the tube is maintained conductive and the circuit therefore corresponds in this respect to the one shown in Fig. 1.

Instead of producing the auxiliary potential, which is important for the limiting or defining of the test in terval, by attectingthe magnets M and M of the switch RW, it may be produced ditfer ently, e.g.,.by switching in an auxiliary current source by means of contact devices which are in suitable-manner controlled by the- Vswitch RW. Such contact devices must of course be provided so as to produce an interval for the testing which when reliable stopping cannot Changes maybe made within the scope and spirit of the appended claims- I claim: V. I 1 f I l. In an automatic telephone :swltch ha ving circuit means including discharge tuberneans lwhich coope :ate

in testing the idle and busy conditions. of lines accessible to the switchover corresponding bank coritatsflrespm tively associated withsaid lines and engaged; byinovable wiper means formingpart of said switch, a circuit arrangement for limiting the testing time; interval, comprising means for enabling said discharge tube means to stop the switch with its wiper means in engagement with bank contacts of an idle line only in the simultaneous presence of an auxiliary .potential acting on said dischargetube means, and means for iconnecting such auxiliary potential only on ce within an interval determined by the movement of said wiperv means over the corresponding bank-contacts during which interval the stopping of the movement oi said wiper. means can'be reliably accomplishedr 2. ,A structure and co-operation of parts as set forth in claim 1, comprising means for'co'nnec ting said auxiliary designated by setting the wiper of thes witch MW on the bank contact 2, at a time when'the wiper c of the 7 switch RW engages the bank contact associated with 7 group II, because, in such acase, the voltage source -72 volt which is raisedto 66 volt. at the occurrence of the impulse P (+6 volt) causes at the grids G and G the identical potential conditions as they obtain at the cathode of the tube R0 The rectifier G1 limits the potential. at the cathode to -,66- volt,'thereby' also equalizing fluctuationsof the voltage induced the windings II of the magnets M and M The wipers of switch RW of Fig. 2 are stopped the energizationof relay P in' the same manner as-explained with refierence to Fig- 1. Relay P also has" a contact In Fig. 3, the potential (e.g., +30 volt), serving for defining and limiting the testing interval, is derived over capacitances directly from "the magnets M and M with- I out resort to second windings. The potential is conducted to agrid G (e.g., a screen grid)'which normally lies on '9O voltover the resistor Wi At the} grid G is thereby produced a voltage, upon engagement; of the wiper c with the private conductor of an idle line; which causes the tube R0 to become conductive so as to stop the switch RW, it being of course assumed that the switch MW an the wiper'd have been set explainedin con- 75" 2647 7 induction in'said magnets.

potential" to a grid of said discharge tube' rn'eans' 3. A sturcture and co-operation of. partsv as set forth in claimil, comprising means for, connecting said: auxiliary potential to the cathode of said discharge tube means.

4. A' structure'and co-operation of parts as set in claim 1, comprising magnets tor driving the .w'ipersof said switch, said auxiliary potentialbemg produced by 5. A structure and ec-operation of parts. as-set forth in calim 1, wherein a discharge space of said discharge tube'means is'connectcd inthe busy test circuit of'bank contact associated with lines reached by the switch wipers to cause said tube means to become conductive by the effect of a potential-on; the bankcontactsof a lineindicating that said line is idle, a current flowing; thereafter over said line and said'discharge'space' which causes abreakdown of the firing potential-of said tube means to the pass a potential which forms the busy potential placed on the bank contacts of the corresponding idle line mark such line as a seized line. v a r 6. A'structure' and co-operation ofpar'ts as defined in claim 5, comprising -a further, discharge tuber a transformer, said space discharge afiecting thej primarywmding of said transformer to produce acurrent in thesecondary winding thereof for firing said further discharge tube.

v. 7. A- structure and co-operation of parts-as defined in claim 6; comprising arelay actuated; responsive t'o'firing of said further discharge tube,-'and circui tmeans con-- trolled by said relay for stopping said switch andfor taining the busy potential on the seized line. 

